STIP1 polypeptides and uses thereof

ABSTRACT

The present invention is directed toward pharmaceutical compositions comprising an isolated polypeptide and a pharmaceutically acceptable carrier. The present invention also discloses an antibody or an antigen-binding portion thereof that bind to the isolated polypeptide. Methods of inhibiting cancer cells growth are also disclosed, comprising administering the isolated polypeptide or the antibody described herein to a subject in need thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 14/172,017, filed on 4 Feb. 2014, which claims the benefit of U.S.Application No. 61/760,597, filed on 4 Feb. 2013, the entire disclosuresof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Stress-induced phosphoprotein (STIP1, SEQ ID NO:3) is a 62.6 kDaprotein, also known as heat shock protein (HSP)-organizing protein(HOP), because it has been shown to modulate the chaperone activities ofHSP 90 and HSP 70. STIP1 contains nine tetratricopeptide repeat (TPR)motifs and one nuclear localization signal (NLS) (Longshaw et al.,2004). The TPR domains of STIP1 are involved in holding HSP70 and HSP90together in the HSP90 chaperone machinery (Odunuga et al., 2004). Thisformation of protein complexes participates in several cellularprocesses, including transcription, protein folding, proteintranslocation, viral replication, signal transduction, and celldivision.

Cancer remains a major public health problem worldwide. It profoundlyaffects more than 1 million people in the U.S. diagnosed each year, aswell as their families and friends. Despite the advance in chemotherapyover the last 50 years, the medical community is still faced with thechallenge for curing many different types of cancer. Accordingly, thereis still a need for the development of effective and safe treatments forvarious types of cancer. The present invention addresses this need.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the present invention discloses a pharmaceuticalcompositions comprising an isolated polypeptide, where the isolatedpolypeptide comprises an amino acid sequence at least 90% homologous toSEQ ID NO:1. The pharmaceutical composition can further comprise anantibody against STIP1.

In another embodiment, the present invention discloses an antibody, oran antigen-binding portion which binds to an amino acid sequence atleast 90% homologous to SEQ ID NO:1.

In yet another embodiment, the present invention provides apharmaceutical composition comprising an antibody or an antigen-bindingportion which binds to an amino acid sequence at least 90% homologous toSEQ ID NO:1; and a pharmaceutically acceptable carrier.

The present invention is also directed to methods for inhibiting cancercell growth, comprising administering (i) an isolated polypeptidecomprising an amino acid sequence at least 90% homologous to SEQ ID NO:1to a subject in need thereof or (ii) an antibody or an antigen-bindingportion thereof binding to an amino acid sequence at least 90%homologous to SEQ ID NO:1 to a subject in need thereof.

The invention also discloses an isolated polypeptide, comprising anamino acid sequence at least 90% homologous to SEQ ID NO:1.

The invention will become more apparent when read with the accompanyingfigures and detailed description which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 illustrates the immunohistochemical analysis of STIP1 (expressedas histoscore) in various cancer cells and the corresponding normaltissues.

FIG. 2 illustrates the presence of various STIP1 polypeptides (SEQ IDNOS: 4-25) in nasopharyngeal cancer (NPT-TWO4), lung cancer (CL1-5), andhepatocellular carcinoma (Hep3B).

FIG. 3 illustrates the cytotoxic effects of STIP1 antibody in ovariancancer cells (MDAH2774), endometrial cancer cells (RL95-2), pancreaticcancer cells (BXPC3), nasopharyngeal cancer cells (NPC-BM1), lung cancercells (CL1-0), colon cancer cells (HT29), and breast cancer cells(MCF7).

FIG. 4 illustrates the cleaved caspase 3 level in STIP1antibody-transfected SKOV3 cells (lower panel) and controlIgG-transfected SKOV3 cells (upper panel).

FIG. 5A illustrates the endogenous STIP1 level in various ovarian cancercell lines (BG1, BR, TOV112D, TOV21G, MDAH2774, SKOV3, ES2 and OV90) andin an endometrial cancer cell line (RL95-2).

FIG. 5B illustrates the cytotoxic effect of STIP1 antibody as comparedwith a control IgG in an ES2 cell line and TOV21G cell line.

FIG. 6A illustrates the SMAD1/5 phosphorylation effect of recombinanthuman STIP1 protein (rh STIP1) on various cancer cell lines.

FIG. 6B illustrates the suppression of SMAD1/5 phosphorylation by STIP1antibody.

FIG. 6C illustrates the effect of rhSTIP1 and STIP1 antibody on ovariancancer cell migration.

FIG. 7A illustrates the effect of DMSO, ALK inhibitors (LDN193189) andERK inhibitor (PD98059) on BrdU incorporation.

FIG. 7B illustrates the effect of DMSO, ALK inhibitors (LDN193189) andERK inhibitor (PD98059) on Ki67 immunocytochemistry.

FIG. 7C illustrates the effect of rhSTIP1, control IgG as compared withSTIP1 antibody on BrdU incorporation.

FIG. 7D illustrates the effect of control IgG as compared with STIP1antibody on Ki67 immunocytochemistry.

FIG. 7E illustrates the effect of control siRNA, ALK2 siRNA andSTIP1siRNA on BrdU incorporation.

FIG. 7F illustrates the effect of control siRNA, ALK2 siRNA andSTIP1siRNA on Ki67 immunocytochemistry.

FIG. 8A illustrates the effect of STIP1 antibody on MOSEC cells.

FIG. 8B and FIG. 8C illustrate the change in tumor volume in STIP1antibody-treated mice as compared with control IgG treated mice.

FIG. 8D illustrates the survival time in STIP1 antibody-treated mice ascompared with control IgG treated mice.

FIG. 9A illustrates the binding affinity of STIP1 antibody to a panel ofoverlapping STIP1 amino acid (a.a.) sequences, including rhSTIP1(control), a.a. sequence number 445-469 (SEQ ID NO: 26), 458-482 (SEQ IDNO: 27), 470-494 (SEQ ID NO: 28), 482-506 (SEQ ID NO: 2), 495-519 (SEQID NO: 29), 507-531 (SEQ ID NO: 30), and 520-543 (SEQ ID NO: 1).

FIG. 9B illustrates the neutralizing effect of various concentrations ofSTIP1 polypeptide 520-543 (peptide 520) on STIP1 antibody.

FIG. 10A illustrates cancer cell (MDAH2774) viability in group treatedwith STIP1 antibody alone, and groups treated with the combination ofSTIP1 antibody and various concentrations of STIP1 polypeptide 520-543(SEQ ID NO:1).

FIG. 10B illustrates cancer cell (MDAH2774) viability in groups treatedwith various concentrations of STIP1 polypeptide 520-543 (SEQ ID NO:1)and other STIP1 polypeptides (SEQ ID NO: 26, 27 and 29).

FIG. 11A and FIG. 11B are microscopic images illustrating the presenceof STIP1 polypeptide 520-543 in the cytosol of the ovarian cancer cells.

FIG. 12 shows the effect of STIP1 polypeptide 520-543 on HSP90 and STIP1interaction.

FIG. 13A and FIG. 13B are bar graphs illustrating the effect of STIP1polypeptide 520-543 (peptide 520) on LDH activity and MTT activity ofthe tested cancer cell lines.

FIG. 14 shows the size of the tumor mass in mice treated with STIP1polypeptide 520-543 (peptide 520) as compared with a control.

FIG. 15 is an assembly of Western Blot images. FIG. 15 A shows theeffect of various concentrations of STIP1 polypeptide 520-543 (peptide520) on JAK2 and pSTAT3 proteins in ovarian and endometrial cancercells. FIG. 15B shows the effect of STIP1 polypeptide 520-543 (peptide520) on JAK2 and Bc1-x1 proteins.

DETAILED DESCRIPTION OF THE INVENTION

Definition

As employed above and throughout the disclosure, the following terms,unless otherwise indicated, shall be understood to have the followingmeanings

As used herein, the singular forms “a,” “an,” and “the” include theplural reference unless the context clearly indicates otherwise.

An “effective amount,” as used herein, includes a dose of an agent thatis sufficient to reduce the symptoms and signs of cancer, which include,but are not limited to, weight loss, pain and tumor mass, which isdetectable, either clinically as a palpable mass or radiologicallythrough various imaging means, such as pain, weight loss or massdemonstrated on radiological images. Alternatively, an effective amountof the agent may be assessed using any other diagnostic means such asserum detection of circulating antigens or other tumor markers using anantibody-based assay (e.g., ELISA).

The term “treating,” “treated,” or “treatment” as used herein includespreventative (e.g. prophylactic), palliative, and curative uses orresults.

The term “inhibiting” and “suppressing” includes, but is not limited to,decreasing, slowing or stopping the growth of

The term “subject” as used herein includes, but is not limited to, anorganism such as a mammal, e.g., a human, non-human primate (e.g.,baboon, orangutan, monkey), mouse, pig, cow, goat, cat, rabbit, rat,guinea pig, hamster, horse, monkey, sheep, or other non-human mammal; anon-mammal, including, e.g., a non-mammalian vertebrate, such as a bird(e.g., a chicken or duck) or a fish, and a non-mammalian invertebrate.Preferably, the subject is a human.

All numbers herein may be understood to be modified by “about.”

The terms “STIP antibody” and “antibody against STIP1” are usedinterchangeably.

In an embodiment, one or more of the therapeutic agents that can be usedin the methods of the present invention for preventing and/or treatingconditions discussed above are formulated with a pharmaceuticallyacceptable carrier, vehicle or adjuvant. The term “pharmaceuticallyacceptable carrier, vehicle or adjuvant” refers to a carrier, vehicle oradjuvant that may be administered to a patient, together with thepresent compounds, and which does not destroy the pharmacologicalactivity thereof and is nontoxic when administered in doses sufficientto deliver a therapeutic amount of the compound.

The compound may be formulated as a salt such as a pharmaceuticallyacceptable salt form, which includes, but are not limited to, acidaddition salts formed with inorganic acids (e.g. hydrochloric acid,hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid, and thelike), and salts formed with organic acids such as, but not limited to,acetic acid, oxalic acid, tartaric acid, succinic acid, malic acid,fumaric acid, maleic acid, ascorbic acid, benzoic acid, tannic acid,pamoic acid, alginic acid, polyglutamic, acid, naphthalene sulfonicacid, naphthalene disulfonic acid, and polygalacturonic acid.Pharmaceutically acceptable salts also include base addition salts whichmay be formed when acidic protons present are capable of reacting withinorganic or organic bases. Suitable pharmaceutically-acceptable baseaddition salts include metallic salts, such as salts made from aluminum,calcium, lithium, magnesium, potassium, sodium and zinc, or salts madefrom organic bases including primary, secondary and tertiary amines,substituted amines including cyclic amines, such as caffeine, arginine,diethylamine, N-ethyl piperidine, histidine, glucamine, isopropylamine,lysine, morpholine, N-ethyl morpholine, piperazine, piperidine,triethylamine, trimethylamine. All of these salts may be prepared byconventional means from the corresponding compound of the invention byreacting, for example, the appropriate acid or base with the compound ofthe invention. Handbook of Pharmaceutical Salts: Properties, and Use (P.H. Stahl & C. G. Wermuth eds., Verlag Helvetica Chimica Acta, 2002) [1].

Pharmaceutically acceptable carriers, adjuvants and vehicles that may beused in the dosage forms of this invention include, but are not limitedto, ion exchangers, alumina, aluminum stearate, lecithin,self-emulsifying drug delivery systems (SEDDS) such as d-E-tocopherolpolyethyleneglycol 1000 succinate; surfactants used in pharmaceuticaldosage forms such as Tweens or other similar polymeric deliverymatrices; serum proteins such as human serum albumin; buffer substancessuch as phosphates, glycine, sorbic acid, potassium sorbate, partialglyceride mixtures of saturated vegetable fatty acids, water, salts; orelectrolytes, such as protamine sulfate, disodium hydrogen phosphate,potassium hydrogen phosphate, sodium chloride, zinc salts, colloidalsilica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-basedsubstances, polyethylene glycol, sodium carboxmethylcellulose,polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers,polyethylene glycol and wool fat. Cyclodextrins such as alpha, beta andγ-cyclodextrin, or chemically modified derivatives such ashydroxyalkylcyclodextrins, including 2- and 3-hydroxypropyl-betacyclodextrins, or other solubilized derivatives may also beadvantageously used to enhance delivery of compounds of the formulaedescribed herein that can be used in the methods of the presentinvention for preventing and/or treating fibrotic conditions. Additionalsuitable excipients may be found in Handbook of PharmaceuticalExcipients, R. C. Rowe, et. al., Pharmaceutical Press, 2009 [9]. Incertain embodiments, unit dosage formulations are compounded forimmediate release, though unit dosage formulations compounded fordelayed or prolonged release of one or both agents are also disclosed.

In one embodiment, the therapeutic agents that can be used in thepresent methods are formulated in a single unit dose such that theagents are released from the dosage at different times.

The Method of Suppressing Cancer Growth

In one embodiment, the invention is directed to methods of reducing orinhibiting cancer cell growth in a subject, the method comprisingadministering an isolated polypeptide which is at least 90% homologousto SEQ ID NO:1, to inhibit cancer cell growth and reduce the signs andsymptoms of cancer in the subject. In one embodiment, the isolatedpolypeptide comprising an amino acid sequence having 90, 91, 92, 93, 94,95, 96, 97, 98, 99 or 100% identity to the amino acid sequence shown inSEQ ID NO:1.

The isolated polypeptides can be used alone, or in combination with aSTIP1 suppression agent to inhibit or reduce cancer cell growth.

The STIP1 suppression agent may be a STIP1 antibody or an antibodyagainst the full-length human STI1 protein (SEQ ID NO:3) or an antibodyagainst a partial sequence. Non limiting examples of STIP1 antibodyinclude, STIP1 MaxPab mouse polyclonal antibody which is available fromAbnova Biotechnology Inc., (Taipei City, Taiwan), or monoclonal STIP1antibody which is commercially available from Sigma-Aldrich(Switzerland). The STIP1 suppression agent can also be a smallinterfering RNA (e.g, siRNA, short interfering RNA or silencing RNA)targeting STIP1 RNA transcripts to decrease the expression of STIP1. Forexample, the STIP1 suppression agent can be a biosynthetic precursor ofa STIP1 targeted small interfering RNA. Small interfering RNAs aretypically short (e.g., about 21 nucleotides in length) double-strandedRNA species with phosphorylated 5′ ends and hydroxylated 3′ ends withtwo overhanging nucleotides. The STIP1 suppression agent can be any RNAspecies, including, but not limited to, microRNA (miRNA), short hairpinRNA, endoribonuclease-prepared siRNA (esiRNA), natural antisense shortinterfering RNA (natsiRNA), where the RNA species targets STIP1 RNA todecrease the expression of STIP1 in the cell(s).

In yet another embodiment, the invention discloses methods of reducingor inhibiting cancer cell growth in a subject comprising administeringan antibody or an antigen-binding portion, which binds to an amino acidsequence at least 90% homologous to SEQ ID NO:1

The cancer may be any solid or hematological tumor, such as, forexample, ovarian, endometrial, nasopharyngeal carcinoma, liver, breast,lung, gastric, pancreatic, colon, leukemias, lymphomas, CNS tumors, suchas glioblastomas, or a sarcoma. In one embodiment, the cancer is can bepancreatic cancer, endometrial cancer, lung cancer, nasopharyngealcarcinoma, breast cancer and colon cancer. Alternatively, in anotherembodiment, the subject is substantially free of ovarian cancer.

Treatment with the antibody or the antigen binding fragment thereofand/or the isolated polypeptide described herein may be administeredalone, or as an adjuvant to surgery, cryotherapy or radiation therapy,e.g., before surgery to reduce the tumor size and/or following surgeryto reduce the possibility of recurrences and metastases, e.g., byinhibition of the growth and migration of circulating tumor cellsthrough the blood stream.

Treatment can be administered before, after or simultaneously with ananti-cancer agent.

The anti-cancer agent includes conventional chemotherapeutic agent,target cancer therapy or radiation therapy. In certain instances, thetreatment includes a combination of various anti-cancer agents.

The dosage of the antibody or antigen binding fragment binding to anamino acid sequence at least 90% homologous to SEQ ID NO:1, or theisolated polypeptide comprising an amino acid sequence at least 90%homologous to SEQ ID NO:1 can be determined by a skilled person in theart, which varies in accordance with the age, weight, and condition ofthe subject to be treated, without undue experimentation.

The antibody or antigen binding fragment which binds to an amino acidsequence at least 90% homologous to SEQ ID NO:1, or the isolatedpolypeptide comprising an amino acid sequence at least 90% homologous toSEQ ID NO:1 can be administered by any suitable routes includingintracranial, intracerebral, intraventricular, intrathecal, intraspinal,oral, topical, rectal, transdermal, subcutaneous, intravenous,intramuscular intranasal, intraperitoneum, intratumor and the like, andcan be encapsulated in a carrying agent such as liposome.

Antibody

As used herein, the term “antibody” includes polyclonal, monoclonal,chimeric, humanized, Fv, Fab and F(ab′)₂; bifunctional hybrid (e.g.,Lanzavecchia et al., Eur. J. Immunol. 17:105, 1987), single-chain(Huston et al., Proc. Natl. Acad. Sci. USA 85:5879, 1988; Bird et al.,Science 242:423, 1988); and antibodies with altered constant regions(e.g., U.S. Pat. No. 5,624,821).

A monoclonal antibody is a single molecular species of antibody, whereasa polyclonal antibody, which is produced by injecting an animal (such asa rodent, rabbit or goat) with an antigen, and extracting the serum fromthe animal. A humanized antibody is a genetically engineered(monoclonal) antibody in which the CDRs from a mouse antibody (“donorantibody”, which can also be rat, hamster or other similar species) aregrafted onto a human antibody (“acceptor antibody”). Humanizedantibodies can also be made with less than the complete CDRs from amouse antibody. Thus, a humanized antibody is an antibody having CDRsfrom a donor antibody and variable region framework and constant regionsfrom a human antibody. Typically, a humanized antibody comprises (i) alight chain comprising three CDRs from a mouse antibody, a variableregion framework from a human antibody, and a human constant region, and(ii) a heavy chain comprising three CDRs from a mouse antibody, avariable region framework from a human antibody and a human constantregion. A chimeric antibody is an antibody in which the variable regionof a mouse (or other rodent) antibody is combined with the constantregion of a human antibody; their construction by means of geneticengineering is well-known in the art (see e.g., Imai et al., Comparingantibody and small molecule therapies for Cancer. Nature Reviews Cancer6:714-727 (2006); see also, BioAtla, 11011 Torreyana Road, San Diego,California 92121)). Such antibodies retain the binding specificity ofthe mouse antibody, while being about two-thirds human. The proportionof nonhuman sequence present in mouse, chimeric and humanized antibodiessuggests that the immunogenicity of chimeric antibodies is intermediatebetween mouse and humanized antibodies. Other types of geneticallyengineered antibodies that may have reduced immunogenicity relative tomouse antibodies, include human antibodies made using phage displaymethods (Dower et al., WO91/17271; McCafferty et al., WO92/001047;Winter, WO92/20791; and Winter, FEBS Lett. 23:92, 1998, each of which isincorporated herein by reference) or using transgenic animals (Lonberget al., WO93/12227; Kucherlapati WO91/10741, each of which isincorporated herein by reference).

The antibody of the invention is typically substantially purified awayfrom undesired contaminants. This means the antibody is typically atleast about 50% w/w (weight/weight) pure, as well as being substantiallyfree from interfering proteins and contaminants. Preferably the antibodyis 91, 92, 93, 9, 95, 96, 97, 98, or 99% w/w pure.

An antibody or an antigen binding fragment that binds to an amino acidsequence is at least 90% homologous to SEQ ID NO:1 is said to inhibitone or more biological activities of STIP1, such as SMAD1/SMAD5phosphorylation, ERK1/ERK2 phosphorylation, ID3 gene expressionactivation, stimulate DNA synthesis stimulation and cell proliferation.

An antibody or an antigen binding fragment thereof that binds to anamino acid sequence at least 90% homologous to SEQ ID NO:1 includesantibodies in their natural tetrameric form (2 light chains and 2 heavychains) and may be of any of the known isotypes, i.e., IgG, IgA, IgM,IgD and IgE as well as their subtypes, i.e., human IgG1, IgG2, IgG3,IgG4 and mouse IgG1, IgG2a, IgG2b, and IgG3. In another embodiment, theantibody or the antigen binding portion binds an amino acid sequence atleast 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%homologous to SEQ ID NO:1.

The antibodies of the present invention can be recovered from a subject,such as human, by selecting one or more B cells that produces one ormore antibodies against SEQ ID NO:1, and recovering said antibodies fromthe B cells. Mouse antibodies against SEQ ID NO:1 are made by standardmethods well-known in the art. In one embodiment, the steps of making anantibody which binds to an amino acid sequence at least 90% homologousto SEQ ID NO:1 include: immunizing a subject, such as an animal, with apeptide having an amino acid sequence comprising SEQ ID NO:1 in anappropriate adjuvant intraperitoneally, intravenously, or subcutaneouslyinto the footpad, followed by extraction of spleen or lymph node cellsof the animal, followed by fusion with a suitable immortalized cell linefor formation of hybridoma(s), and then selecting the hybridoma(s) thatproduce antibody binding to amino acid sequence at least 90% homologousto SEQ ID NO:1. The immunized animal can be any animal that is capableof producing recoverable antibodies when administered an immunogen, suchas, but not limited to, rabbits, mice, rats, hamsters, goats, horses,monkeys, baboons and humans. After the host is immunized and theantibody against SEQ ID NO:1 is produced, the antibody is assayed toconfirm that they are specific for the antigen of interest and todetermine whether they exhibit any cross reactivity with any otherantigens. One method of conducting such assays is a sera screen assay asdescribed in U.S. Patent Publication No. 2004/0126829. Antibody againstSEQ ID NO:1 can be characterized for binding to the polypeptide antigen(e.g., SEQ ID NO:1) by a variety of known techniques. For example, in anELISA, microtiter plates are coated with the toxin or toxoid antigen inPBS, and then blocked with irrelevant proteins such as bovine serumalbumin (BSA) diluted in PBS. Dilutions of plasma from toxin-immunizedmice are added to each well and incubated. The plates are washed andthen incubated with a secondary antibody conjugated to an enzyme (e.g.,alkaline phosphatase). After washing, the plates are developed with theenzyme's substrate (e.g., ABTS), and analyzed at a specific OD. In otherembodiments, to determine if the selected monoclonal antibodies bind tothe polypeptide antigen (e.g., SEQ ID NO:1), the antibody can bebiotinylated and the labeled antibodies detected with a streptavidinlabeled probe. The antibodies can be tested for reactivity with thepolypeptide antigen (e.g., SEQ ID NO:1) by Western blotting.

The antibodies which bind to an amino acid sequence at least 90%homologous to SEQ ID NO:1 can also be made by phage display ortransgenic mice methods well-known in the arts. In one aspect, the hostis transgenic and produces human antibodies, e.g., a mouse expressingthe human immunoglobulin gene segments. U.S. Pat. Nos. 8,236,311;7,625,559 and 5,770,429, the disclosure of each of which is incorporatedherein by reference in its entirety. Lonberg et al., Nature 368(6474):856-859, 1994. Lonberg, N., Handbook of Experimental Pharmacology113:49-101, 1994. Lonberg, N. and Huszar, D., Intern. Rev. Immunol., 13:65-93, 1995. Harding, F. and Lonberg, N., Ann. N.Y. Acad. Sci.,764:536-546, 1995. In one embodiment, the antibody can be made by thefollowing steps: immunizing a subject with a polypeptide comprising SEQID NO:1; recovering mRNA from a B cells of said subject; converting saidrecovered mRNA to cDNA; expressing said cDNA in phages such that anantibody encoded by said cDNA are then presented on the surface of saidphages; selecting phages that present said antibody; recovering nucleicacid molecules from said selected phages that encode said antibody;expressing said recovered nucleic acid molecules in a host cell; andrecovering antibody from said host cell that binds an amino acidsequence comprising SEQ ID NO:1.

Genetically engineered antibody against SEQ ID NO:1, e.g., chimericantibody, may be expressed by a variety of well known art-known methods.For example, genes encoding their light and heavy chain V regions may besynthesized from overlapping oligonucleotides and inserted together withavailable C regions into expression vectors (e.g., commerciallyavailable from Invitrogen) that provide the necessary regulatoryregions, e.g., promoters, enhancers, poly A sites, etc. Use of the CMVpromoter-enhancer is preferred. The expression vectors may then betransfected using various well-known methods such as lipofection orelectroporation into a variety of mammalian cell lines such as CHO ornon-producing myelomas including Sp2/0 and NSO, and cells expressing theantibodies selected by appropriate antibiotic selection. See, e.g., U.S.Pat. No. 5,530,101. Larger amounts of antibody may be produced bygrowing the cells in commercially available bioreactors.

Once expressed, the antibody against SEQ ID NO:1 may be purifiedaccording to standard procedures of the art such as microfiltration,ultrafiltration, protein A or G affinity chromatography, size exclusionchromatography, anion exchange chromatography, cation exchangechromatography and/or other forms of affinity chromatography based onorganic dyes or the like.

Pharmaceutical Composition

In one aspect, the present invention provides pharmaceutical compositioncomprising an isolated polypeptide comprising an amino acid sequence atleast 90% homologous to SEQ ID NO:1 and a pharmaceutically acceptablecarrier. In another embodiment, the pharmaceutical composition furthercomprises an antibody against the full-length human STIP1 protein (SEQID NO:3).

The isolated polypeptides of the pharmaceutical composition are at least90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% homologous to the aminoacid sequence of SEQ ID NO:1.

In one embodiment, the isolated polypeptide of the pharmaceuticalcomposition differs from SEQ ID NO:1 by a small number of functionallyinconsequential, amino acid substitutions (e.g., conservativesubstitutions), deletions, or insertions, while retaining the functionalproperties of SEQ ID NO:1, i.e., such polypeptide inhibits the cancercell growth in at least one, and preferably all, in vitro or in vivoassays described herein. For purposes of classifying amino acidssubstitutions as conservative or nonconservative, amino acids may begrouped as follows: Group I (hydrophobic side chains): norleucine, met,ala, val, leu, ile; Group II (neutral hydrophilic side chains): cys,ser, thr; Group III (acidic side chains): asp, glu; Group IV (basic sidechains): asn, gln, his, lys, arg; Group V (residues influencing chainorientation): gly, pro; and Group VI (aromatic side chains): trp, tyr,phe. Conservative substitutions involve substitutions between aminoacids in the same class. Non-conservative substitutions constituteexchanging a member of one of these classes for a member of another.

In one embodiment, the isolated polypeptide differs from SEQ ID NO:1 byup to 5 amino acids change, such as 1, 2, 3, 4, or 5 amino acids change.

The present invention also discloses pharmaceutical compositionscomprising an antibody or antigen binding fragment which binds to apeptide having an amino acid sequence at least 90% homologous to SEQ IDNO:1.

The pharmaceutical compositions may further comprise a signal peptidethat facilitates the entry into the cell (Horibe et al. J TranslationMed 9:8, 2011), physiologically acceptable carrier, optionally withexcipients or stabilizers, in the form of lyophilized or aqueoussolutions. Acceptable carriers, excipients or stabilizers are nontoxicto recipients at the dosages and concentrations employed, and includebuffers such as phosphate, citrate, or acetate at a pH typically of 5.0to 8.0, most often 6.0 to 7.0; salts such as sodium chloride, potassiumchloride, etc. to make isotonic; antioxidants, preservatives, lowmolecular weight polypeptides, proteins, hydrophilic polymers such aspolysorbate 80, amino acids, carbohydrates, chelating agents, sugars,and other standard ingredients known to those skilled in the art.

The pharmaceutical compositions of the present invention can be preparedas injectables, either as liquid solutions or suspensions, or as solidforms which are suitable for solution or suspension in liquid vehiclesprior to injection. The pharmaceutical composition can also be preparedin solid form, emulsified or the active ingredient encapsulated inliposome vehicles or other particulate carriers used for sustaineddelivery. For example, the pharmaceutical composition can be in the formof an oil emulsion, water-in-oil emulsion, water-in-oil-in-wateremulsion, site-specific emulsion, long-residence emulsion,stickyemulsion, microemulsion, nanoemulsion, liposome, microparticle,microsphere, nanosphere, nanoparticle and various natural or syntheticpolymers, such as nonresorbable impermeable polymers such asethylenevinyl acetate copolymers and Hytrel® copolymers, swellablepolymers such as hydrogels, or resorbable polymers such as collagen andcertain polyacids or polyesters such as those used to make resorbablesutures, that allow for sustained release of the pharmaceuticalcomposition.

The following examples further illustrate the present invention. Theseexamples are intended merely to be illustrative of the present inventionand are not to be construed as being limiting.

Material and Methods

1. Preparation of Cell Culture

Human ovarian cancer cell lines TOV112D, TOV21G, SKOV3, MDAH2774, ES2,MDAH2774,BG1; human endometrial cancer cell line RL95-2, humanpancreatic cancer cell line BxPC3, breast cancer cell line (MCF7) andcolon cancer cell line (HT29) were obtained from ATCC (Rockville, Md.,USA). Lung cancer cell line CL1-0 and nasopharyngeal carcinoma cell lineNPC-BM1 were obtained from Dr. CC Wu (Department of MedicalBiotechnology and Laboratory Science, Chang-Gung University, Taoyuan,Taiwan), Wu et al. Mol. Cell Proteomics 9(6):11100 (20101). Mouseovarian cancer cell line MOSEC was obtained from Dr. CL Chang(Department of Obstetrics and Gynecology, Mackay Memorial Hospital,Taipei, Taiwan) , Chang et al. Cancer Research 67:10047 (2007). TOV112D,TOV21G, SKOV3, MDAH2774, ES2 and RL95-2 were cultured in Dulbecco'smodified Eagle's medium/F-12 supplemented with 10% fetal bovine serumand antibiotics at 37° C. in 5% CO2 humidified atmosphere. BxPC3, CL1-0,NPC-BM1 and MOSEC cells were cultured in RPMI 1640 media supplementedwith 10% fetal bovine serum.

2. Proteomics Analysis of Secreted Proteins from Cancer Cell Lines

The procedures for identifying secreted protein of various cancer celllines were previously reported (Wu et al 2010). Briefly, cancer cellswere grown to confluence in 15-cm culture dishes. The cancer cells werewashed and incubated with serum-free media for 24 h. The supernatantswere harvested and centrifuged to remove cell contaminants. Proteomicsanalysis was performed with one-dimensional SDS-PAGE, in-gel proteindigestion, followed by reverse-phase liquid chromatography/tandem massspectrometry (LC/MS-MS). Protein identification was performed using theopen source TPP software (version 3.3), the SEQUEST search, thePeptideProphet program and the ProteinProphet program.

3. Antibody Transfection

Cancer cells were transfected with an STIP1 antibody in PLUSin reagent(Polyplus-transfection Inc., NY, USA) according to manufacturer'sprotocol. In summary, 2×10³˜6×10³ cancer cells were seeded in a 96-wellplate overnight, followed by PBS rinse and the addition of 180 μl ofOPTI-MEM. 0.6 μg of mouse STIP1 antibody were diluted in 20 mM HEPES,mixed with 1.2 μl of PLUSin by vortexing, followed by incubation at roomtemperature for 15 min. The antibody/PLUSin mixture was added to thecancer cells by gentle swirling the plate. The STIP1 antibody and thecontrol IgG used in the working examples described herein arecommercially available from Abnova Biotechnology Inc., (Taipei City,Taiwan). The STIP1 antibody in the working examples described herein canbe used to detect recombinant full length STIP 1 (SEQ ID NO:3).

4. Cell Migration Assays

BG1 and MDAH2774 cells (10⁶/well) treated with either rhSTIPl (400 nM)or void STIP1 were cultured in serum free medium for 24 h before platedin the upper chamber of the 8-μm pore (24-well) transwell insert(Corning and Transwell, N.Y., USA). The lower chamber was filled with800 μl of DMEM/F12 media and 0.5 μg/ml of fibronection (Sigma, USA).After 26 h of incubation, the cells that had migrated through the poresand reattached to the lower chamber were stained with fluoresceincalcein-AM (4 μg/ml) (BD, USA). The number of viable cells that hadtraversed the filter was determined by the fluorescence of each samplein a Tecan Infinite M200 Multiwell reader (Tecan, Switzerland).Neutralization of STIP1 was performed using STIP1 antibody (800 nM).Each cell migration assay was repeated in three separate occasions.

6. Cell Viability Assay

1˜2×10⁴ Cancer cells were plated per well in 96-well plates overnight,then transfected with a mouse STIP1 antibody (commercially availablefrom Abnova Biotechnology Inc.) for 48 h before they were assessed. Theinhibitory effect of the STIP1 antibody on the cancer cells was measuredby the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-DiphenyltetrazoliumBromide] method (Sigma St. Louis, Mo.). The optical density was measuredat 570 nm using an automated scanning multiwell spectrophotometer(Wallac Victor2 spectrophotometer; PerkinElmer, Boston, Mass., USA).

7. Western Blot Analysis

Cell lysates were prepared with a RIPA buffer (150 mM NaCl, 20mM Tris-ClpH7.5, 1% Triton X-100, 1% NP40, 0.1% SDS, 0.5% deoxycholate) containingfreshly added proteinase and phosphatase inhibitors (Bionovas, Toronto).Protein concentration was measured using the Bradford method. Fifty μgof each sample was electrophoresed in 10% SDS-polyacrylamide gels, andtransferred to nitrocellulose membranes. STIP1 antibody was commerciallyavailable from Abnova Biotechnology and Santa Cruz Biotechnology, SantaCruz, Calif., actin was commercially available from Sigma, thecorresponding horseradish peroxidase-conjugated antibody wascommercially available from Santa Cruz Biotechnology, enhancedchemiluminescence reagent was commercially available from Millipore Inc.(Millipore, Billerica, Mass.). The signal intensity of autoradiogram wasquantified using the UN-SCAN-IT software (Silk Scientific, Orem, Utah),and relative intensity of each sample was normalized by thecorresponding actin intensity. For antibody neutralization assay, cancercells were cultured in serum-free medium for 24 h, and treated withrhSTIPl for another 24 h in the presence or absence of the STIP1monoclonal antibody, which were pre-incubated at 37° C. for 1 h.Endogenous phospho-SMAD1/5 was detected with western blot analysis.

8. Immunohistochemistry (IHC)

Paraffin-embedded ovarian cancer tissues were sectioned to 4 μm, thendeparaffinized with xylene, and rehydrated with ethanol solutions.Ovarian cancer tissue sections were stained with a control mouse IgG oran STIP1 antibody (Abnova, Taipei City, Taiwan), in an automated IHCstainer with Ventana Basic DAB (3,3′-diaminobenzidine) Detection Kit(Tucson, Ariz.). Hematoxylin was used for counterstaining To quantifyimmunointensity of each IHC slide, histoscore was calculated bymultiplying % of cancer cells (0˜100%) with immunointensity (0˜3), aspreviously described (Chao et al 2010, Chao et al 2012). Commerciallyavailable tissue arrays (FDA-805-1 and 2, Biomax Inc., USA) were used todetect tissue distribution of STIP1 in various human organs andcorresponding cancers.

9. Immunofluorescent Microscopy

Cancer cells were cultured on cover slides at a concentration of 3×10⁵cells/well in 6-well plates overnight, followed by serum starvation foranother 24 h. After transfecting with STIP1 antibody for 72 h, cancercells were fixed with 2% of paraformaldehyde at 4° C. for 30 min, andincubated in blocking buffer (5% normal goat serum in PBS) for 1 h atroom temperature, to reduce non-specific binding. Cancer cells wereincubated with an anti-mouse Alexa Fluor-488 (Invitrogen, 1:100) fordetecting the STIP1 antibody and the rabbit polyclonal anti-cleavedcaspase 3 antibody (Cell Signaling Technology, Beverly, Mass., USA,1:100). After incubation with an anti-rabbit Alexa Fluor-546 (1:100,Invitrogen, Carlsbad, Calif.), the slides were mounted with Vectashieldmounting medium (Vector Laboratories, Burlingame, Calif.), and analyzedunder the Leica TCS SP2 laser scanning confocal system (Leica Inc.,Germany).

10. BrdU Proliferation Assay and Ki67 Immunocytochemistry

The BrdU assay and Ki67 staining procedures have been reportedpreviously (Tsai et al 2012, Wang et al 2010). For BrdU assays, cancercells were seeded at a density of 10⁴ cells/well in a 96-well plateovernight, and cultured in serum-free medium for 24 h. Cancer cells weretreated with 0.4 μM of rhSTIP1 in the presence of BrdU for 24 h. DNAsynthesis activity was measured using BrdU ELISA kit (Roche AppliedScience). For immunocytochemistry studies of Ki-67, MDAH2774 cells werecultured on Lab-Tek II chamber slides (Nalge Nunc International,Denmark) overnight. After serum starvation or RNAi transfection for 72h, cancer cells were treated with 0.4 μM of STIP1 with or without anSTIP1 antibody for another 24 h. The slides were fixed with 99.9% ofethanol, rehydrated with PBS, treated with 3% of hydrogen peroxide for20 min, permeabilized with 0.1% Triton X-100 (Sigma) for 15 min, andstained with anti-Ki67 antibody (Thermo Fisher Scientific, Rockford,Ill.).

11. Cell Cytotoxicity Assays

Cells were seeded at 1˜2×10⁴ cell per well of 96-well plates andtransfected with the STIP1 antibody at 37° C. for 48 hours. To assay theactivity of lactate dehydrogenase (LDH), 100 pl of a reaction mixture(Cytotoxicity Detection Kit PLUS®, Roche, Basel, Switzerland) and theconditional medium were added to each well and incubated in the dark for5-20 min. The water-soluble formazan dye displayed a broad absorptionmaximum at approximately 500 nm in the Victor2 ELISA reader. The CellDeath Detection ELISA photometric enzyme immunoassay (Roche) was usedfor in vitro quantitative determination of cytoplasmichistone-associated DNA fragments (mono- and oligonucleosomes) as anindicator of apoptosis. The absorbance was measured at 405 nm.

12. In Vivo Animal Model

Five-week-old female C57BL/6 mice were obtained from the National AnimalCenter, Taiwan, and had free access to water and food during the trial.All of the procedures carried out in the animal study were approved bythe Institutional Animal Care and Use Committee of the Chang GungMemorial Hospital, Taiwan. All of the experiments were conformed to theGuide for the Care and Use of Laboratory Animals published by the USNational Institutes of Health (NIH Publication No.85-23, revised 1996).

13. Tumor Growth Monitoring Using an In Vivo Imaging System

Mouse ovarian surface epithelial cancer cells that expressed luciferase(MOSEC/LUC) were suspended in Hanks' balanced salt solution (HBSS). Eachmouse was injected with 10⁶ of MOSEC cells intraperitoneally, using a 23gauge needle (Becton Dickson, Franklin Lakes, N.J., USA). Each mouse wasinjected with luciferin intraperitoneally (100 μl of 0.4 mg/mLluciferin, Promega) the following day and imaged with an IVIS imagingsystem (Xenogen Corp., Alameda, Calif., USA) 10 min after the injection.All mice were sedated with isoflurane and imaged at the MolecularImaging Core Laboratory of Chang Gung Memorial Hospital, Taiwan. Lightoutputs were quantified using the Livinglmage software (Xenogen Corp.).Raw values were reported as photons/second/cm2/sr.

Results

Detection of STIP1 in Multiple Human Cancers

As illustrated in FIG. 1, ovarian cancer tissue has a much higher STIP1histoscore (over 200) than that of normal ovarian tissue (0). Severalother cancers also had elevated STIP1 histoscore compare to theircorresponding normal tissue, including brain cancer, endometrial cancer,thyroid cancer, lung cancer, stomach cancer, liver cancer, prostatecancer, colon cancer, and skin cancer.

FIG. 2 shows that various STIP1 polypeptides were expressed innasopharyngeal cancer (NPC-TWO4), lung cancer (CL1-5), and liver cancer(Hep3B) cells.

STIP1 Antibody Reduced Cancer Cell Viability and Induced Cancer CellDeath

The following cancer cell lines were transfected using the PLUSinreagent with STIP1 antibodies to block endogenous STIP1: MDAH2774(ovarian cancer), RL95-2 (endometrial cancer), NPC-BM1 (nasopharyngealcancer), BxPC3 (pancreatic cancer), CL1-0 (lung cancer), HT29 (coloncancer), and MCF7 (breast cancer) cells. Cancer cell viability wasassessed using the MTT assay, while cell death was assessed using LDHassay.

FIGS. 3 shows that in all of the tested cancer cell lines, STIP1antibody transfection led to a lower MTT level (less cell viability) anda higher LDH level (more cell death).

Caspase 3 cleavage is also used as an indicator for cell death. Afterthe ovarian cancer cells (SKOV3) was transfected with the STIP1antibody, cleaved caspase 3 level was assessed using immunoflorescentmicroscopy. In FIG. 4, ovarian cancer cells transfected with an STIP1antibody have a higher level of cleaved caspase-3 (lower right panel inFIG. 4) than those cancer cells transfected with a control IgG (upperright panel in FIG. 4).

These results indicate that STIP1 antibody is effective in inhibitingcancer cell growth.

FIG. 5A shows endogenous STIP1 expression level in eight ovarian cancercell lines and one endometrial cancer cell line (RL95-2. Among thesecell lines, the highest endogenous STIP1 expression was in ES2 cell lineand the lowest was in TOV21G cell line. Based on these results, ES2 andTOV21G cell lines were among the most suitable candidates for testingthe effects and the specificity STIP1 antibodies in vitro.

Following STIP1 antibody transfection, ES2 cell line (with highestendogenous STIP1 expression) showed a lower MTT level (less cellviability) and a higher LDH level (more cell death) than TOV21G cells(with lowest endogenous STIP1-expression). See FIG. 5B. Since both ES2cells and TOV21G cells are clear cell ovarian cancer cells, thedifferent cytotoxic effect of STIP1 antibody was due to different STIP1expression level, rather than the different cancer type.

STIP1 Antibody Neutralizes the Effects of Secreted STIP1 on SignalInduction, Cell Proliferation and Migration of Cancer Cells

Without being bound by any theory, it is believed that STIP1 triggersALK2-SMAD1/5 phosphorylation pathway and ID3 pathway to promote ovariancancer cell proliferation. FIG. 6A shows that rhSTIP1 stimulates SMAD1/5phosphorylation in six ovarian cancer cell lines (ES2, SKOV3, TOV21G,TOV112D, BR and BG1), one endometrial cancer cell line (RL95-2), onelung cancer cell line (CL1-0) and one nasopharyngeal carcinoma cell line(NPC-BM1).

STIP1 antibody was administered to verify that SMAD1/5 phosphorylationin FIG. 6A was induced by the interaction between STIP1 and STIP1 cellmembrane receptor. FIG. 6B shows that SMAD1/5 phosphorylation waspartially suppressed by STIP1 antibody at a molarity ratio of 2:1 (STIP1antibody:rhSTIPl), and SMAD1/5 phosphorylation was completely suppressedby STIP1 antibody at a molarity ratio of 4:1 (STIP1 antibody:rhSTIP1).These results suggest that STIP1 antibody can neutralize STIP1secretedby cancer cells.

FIG. 6C shows STIP1 antibody (Ab02 and Ab04) suppressedrhSTIP1-stimulated cell migration.

BrdU is an analogue of thymidine which can replace thymidine during DNAreplication, and Ki67 is a nuclear protein that is associated with cellproliferation. BrdU incorporation assay and immunocytochemistry forendogenous Ki67 were used as an index for cell proliferation. Treatmentwith rhSTIP1 increased the BrdU incorporation rate and Ki67 staining ofovarian cancer cells (FIGS. 7A to FIG. 7F). These activities werereduced by treatment with an ALK2/ALK3 inhibitor (LDN193189) and an ERKinhibitor (PD98059) (FIGS. 7A and 7B), an STIP1 antibody (FIGS. 7C and7D), and ALK2 siRNA and STIP1 siRNA (FIGS. 7E and 7F). Of note,inhibition of ERK activity by PD98059 strongly inhibited cellproliferation, but even in such inhibition, treatment with rhSTIP1 stillsignificantly stimulated BrdU incorporation (FIG. 7A). These resultsindicated that ERK pathways are very important for cell proliferation,but the ALK2-SMAD might be more specific for the rhSTIP1-stimulated cellproliferation. Furthermore, knockdown of endogenous STIP 1 alone did notinhibit cell proliferation and neither did it affect the stimulation ofcell proliferation by exogenous rhSTIP1 (FIGS. 7E and 7F).

These data further support the use of STIP1 antibody to inhibitproliferation and migration of cancer cells.

In Vivo Evaluation of STIP1 Antibody in Cancer Cell Inhibition

Mouse Ovarian Surface Epithelial Cells (MOSEC) are sensitive to thecytotoxic effect of STIP1 antibody (see FIG. 8A). 10⁶ of MOSEC cellswere inoculated into the abdominal cavity of C57BL/6 mice, followed bythe intravenous injection of 100 μg of STIP1 antibody via tail veintwice a week. Tumor growth was assessed 4 weeks later using Xenogen IVIS200 In Vivo Imaging System (Xenogen Corp., Alameda, Calif., USA). FIGS.8B and 8C show that mice treated with STIP1 antibody have a lower tumorvolume as compared to mice treated with control IgG. FIG. 8D shows thatmice treated with STIP1 antibody have a significantly longer survivaltime (median survival time was 59 days) as compared to mice treated withcontrol IgG (median survival time was 53 days).

These results suggest that STIP1 antibody is effective in cancer cellinhibition and prolongs survival.

STIP1 Epitope For Cancer Cell Inhibition

In FIG. 9A, the following STIP1 polypeptides were dot blotted on a nylonmembrane and incubated with an STIP1 antibody: STIP1 polypeptides withamino acid (a.a.) sequence number 445-469, 458-482, 470-494, 482-506(SEQ ID NO:2), 495-519, 507-531, and 520-543 (SEQ ID NO:1). The entirerhSTIP1 (a.a. sequence number 1 to 543) was used as positive control(the left lane). The data showed the STIP1 polypeptide with a.a.sequence number 520-543 (SEQ ID NO:1) have the highest affinity to STIP1antibody used in this assay, followed by the STIP1 polypeptide with a.a.sequence number 482-506 (SEQ ID NO:2).

The entire rhSTIP1 at different concentrations were dot blotted on anylon membrane, and incubated with STIP1 antibody. The STIP1 antibodywas pre-incubated with STIP1 polypeptide 520-543 (SEQ ID NO:1), atvarious antibody/polypeptide concentration ratios (from 1:1 to 1:8).FIG. 9B shows that STIP1 polypeptide 520-543 (SEQ ID NO:1) neutralizedthe binding of STIP1 antibody to rhSTIP1 in a dose dependent fashion.This result further suggests that STIP1 epitope for cancer cellinhibition is located at STIP1 a.a. sequence number 520 to 543 (SEQ IDNO:1).

STIP1 Polypeptide 520-543 (SEQ ID NO:1) Suppresses Cancer Cells

Given the neutralizing effect of STIP1 polypeptide 520-543 (SEQ ID NO:1)on STIP1 antibody, co-transfecting STIP1 antibody and STIP1 polypeptide520-543 in cancer cells may reduce the suppression effect of STIP1antibody. FIG. 10A and Table 1 show cell viability of ovarian cancercells (MDAH2774) transfected with STIP1 antibody only (positive control)and STIP1 antibody with various concentrations of STIP1 polypeptide520-543. Cell viability was evaluated using MTT assays. Unexpectedly,co-transfection of an STIP1 antibody and STIP1 peptide 520-543 in cancercells showed synergistic suppression of cell viability than thetransfection of STIP1 antibody alone. For example, the cell viabilityfor STIP1 antibody was 78.81% (Table 1), the cell viability for 25 uM ofSTIP1 polypeptide 520-543 was 102% (Table 2), and the cell viability forSTIP1 antibody and 25 uM of STIP1 polypeptide 520-543 was 56.38% (Table1). Similarly, the cell viability for 200 uM of STIP1 polypeptide520-543 was 28.64% (Table 2), and the cell viability for STIP1 antibodyand 25 uM of STIP1 polypeptide 520-543 was 27.67% (Table 1).

TABLE 1 Cell Viability of ovarian cancer cells (MDAH2774) transfectedwith STIP1 antibody only (positive control) and STIP1 antibody withvarious concentrations of STIP1 polypeptide 520-543. Positive Neg-control 1:1 1:4 1:8 ative (STIP1 (Ab:pep- (ab:pep- (Ab:pep- control Abonly) tide) tide) tide) Original O.D 1.06 0.83 0.60 0.45 0.29 NormalizedO.D 1 0.78 0.56 0.42 0.28 Cell viability (%) 100 78.82 56.38 42.19 27.67

TABLE 2 Cell Viability of ovarian cancer cells (MDAH2774) transfectedwith various concentrations of STIP1 polypeptide 520-543 (Peptide 520)and other STIP1 polypeptides. Peptide Peptide Peptide Peptide PeptidePeptide Negative 520 520 520 445 458 495 Control 25 uM 150 uM 200 uM 200uM 200 uM 200 uM Original 0.15 0.15 0.10 0.09 0.13 0.13 0.14 O.DNormalized 1 1.02 0.49 0.29 0.86 0.83 0.97 O.D Cell 100 102.14 49.0328.64 85.73 82.57 96.94 viability (%)

FIG. 10B and Table 2 show that STIP1 polypeptide 520-543 suppressescancer cell viability in a dose-dependent fashion, whereas STIP1polypeptides comprising other amino acid sequences 445-469 (peptide 445;SEQ ID NO: 26), 458-482 (peptide 458; SEQ ID NO: 27) and 495-519(peptide 495; SEQ ID NO:29) did not significantly suppress cancer cellviability. Without being bound by any theory, it is believed that STIP1polypeptide 520-543 (SEQ ID NO:1) competitively inhibits STIP1 antibody.

Conclusion: Results in FIGS. 9A to FIG. 10B indicate that suppressingSTIP1 led to reduced cell viability. STIP1 can be suppressed by using anSTIP1 antibody that binds to the an epitope comprising SEQ ID NO:1, orby administering an isolated STIP1 polypeptide having SEQ ID NO:1.

Cell Permeability of STIP1 Polypeptide 520-543 (SEQ ID NO:1)

To verify the cancer cell permeability of STIP1 polypeptide 520-543,ovarian cancer cells (MDAH2774) were treated with 10 uM of STIP1polypeptide 520-543 having eight D-arginine residues for 24 hrs. Theintracellular distribution of STIP1 polypeptide 520-543 was examinedusing anti-myc antibody under immunofluorescent microscopy. FIG. 11Bshows the presence of STIP1 polypeptide 520-543 in the cytosol of theovarian cancer cell.

The Effect of STIP1 Polypeptide 520-543 on HSP90/STIP1 Interaction

The effect of STIP1 polypeptide 520-543 on HSP90 and STIP1 interactionwas evaluated by treating cancer cells with various concentrations ofSTIP1 polypeptide 520-543. HSP90-STIP1 interaction with evaluated usingimmunoprecipitation method.

FIG. 12 shows the binding ability of STIP1 to HSP90 was reduced as theconcentration of STIP1 polypeptide 520-543 increased. This data showsSTIP1 polypeptide 520-543 can prevent STIP1 binding to HSP90 and clientprotein misfolding.

The Effect of STIP1 Polypeptide 520-543 on Cancer Cells

An in vitro evaluation of the effect of STIP1 polypeptide 520-543 oncancer cells was performed.

Cell permeable STIP1 polypeptide 520-543 was added to the followingcancer cell lines: MDAH2774 (ovarian cancer); ARK2 (endometrial cancer);NPC-BM1 (nasopharyngeal cancer); SAS (oral cancer); Colon 205 (coloncancer); CL 1-0 (lung cancer); BxPC3 (pancreatic cancer); HepG2 (livercancer) and MCF7 (breast cancer) cells. Cancer cell viability wasassessed using the MTT assay and cell death was assessed using LDHassay.

FIG. 13A and FIG. 13B show cell permeable STIP1 polypeptide 520-543(peptide 520) inhibits cell proliferation (illustrated by reduced MTTactivity) and induce cell death (illustrated by increased LDH activity)in all of the tested cancer cells.

An in vivo evaluation of the effect of STIP1 polypeptide 520-543 on nudemice was performed.

Nude mice were inoculated with 5×10⁵ cells of human ovarian cancer cellsMDAH2774 subcutaneously. 100 μg of STIP1 polypeptide 520-543 wasadministered three times a week via the tail vein.

FIG. 14 illustrates the size of the tumor mass in mice treated withSTIP1 polypeptide 520-543 is less than that of the control group. Theseresults indicate the in vivo efficacy of STIP1 polypeptide 520-543 inreducing cancer cells.

STIP1 Polypeptide 520-543 Induces the Degradation of JAK2 Protein

One of HSP90 client proteins is JAK2 (Frid et al. JAKSTAT 1(2):77(2012); Marubayashi et al. J. Clin. Invest. 120(10):3578 (2010). TheJAK2-STAT3 pathway plays an important role in tumor transformation andprogression (Miklossy et al., Nat Rev. Drug Discovery: 12(8):611(2013)).

The effect of STIP1 polypeptide 520-543 on HSP90 function was evaluatedusing ovarian cancer cell line (MDAH2774) and endometrial cancer cellline (ARK2). The cancer cell lines were treated various concentrationsof STIP1 polypeptide 520-543.

Forty-eight hours later, the intracellular levels of JAK2 andphosphor-STAT3 were decreased in dose dependent manner, as illustratedin FIG. 15A. In addition, JAK2 and Bc1-XL proteins were down-regulatedin presence of STIP1 polypeptide 520-543, as illustrated by western blotin FIG. 15B. These results demonstrate that STIP1 polypeptide 520-543induces cell death by blocking the JAK2-STAT3-Bc1 XL pathway.

Production of Monoclonal Antibodies Reactive to SEQ ID NO:1 Polypeptide

BALB/c mice will be immunized intraperitoneally 3-4 times at 2-4 weeklyintervals, with SEQ ID NO:1 polypeptide and challenged 3 days prior tospleen-cell removal with SEQ ID NO:1 polypeptide. A spleen-cellsuspension will be prepared, fused with the myeloma NS1/1 AG4.1 andhybridomas grown up and cloned. Initially, hybridoma culturesupernatants will be tested for reactivity with SEQ ID NO:1 polypeptideby immunofluorescence flow cytometry (FACS). Briefly, SEQ ID NO:1polypeptide will be incubated (30 min, 4.degree. C.) with undilutedhybridoma supernatant, washed and incubated withfluorescein-isothiocyanate (FITC)-sheep F(ab′)2 anti-mouse Ig(100ug/ml). Following final washing, monoclonal antibody binding to SEQ IDNO:1 polypeptide will be examined by FACS analysis. Positive hybridomasupernatants will be screened on the human melanoma cell line MM-170 toeliminate non-endothelial specific mAbs. Binding specificity to SEQ IDNO:1 polypeptide will be further confirmed by screening of monoclonalantibodies on a panel of human tumor cell lines as well as humanlymphocytes, monocytes, neutrophils, red cells and platelets.

All references cited and discussed in this specification areincorporated herein by reference in their entirety. Variations,modifications and other implementations of what is described herein willoccur to those of ordinary skill m the art without departing from thespirit and scope of the invention. While certain embodiments of thepresent invention have been shown and described, it will be obvious tothose skilled in the art that changes and modifications may be madewithout departing from the spirit and scope of the invention. The matterset forth in the foregoing description and accompanying drawings isoffered by way of illustration only and not as a limitation.

Sequence Listing Stress-induced phosphoprotein 1 peptide 520(amino acid position 520-543 of full-length STIP1) SEQ ID NO: 1EHLKNPVIAQKIQKLMDVGLIAIR Stress-induced phosphoprotein 1 peptide 482(amino acid position 482-506 of full-length STIP1) SEQ ID NO: 2PEDVKRRAMADPEVQQIMSDPAMRLStress-induced phosphoprotein 1 [Homo sapiens]|GenBank Accession No. NP_006810 SEQ ID NO: 3MEQVNELKEKGNKALSVGNIDDALQCYSEAIKLDPHNHVLYSNRSAAYAKKGDYQKAYEDGCKTVDLKPDWGKGYSRKAAALEFLNRFEEAKRTYEEGLKHEANNPQLKEGLQNMEARLAERKFMNPFNMPNLYQKLESDPRTRTLLSDPTYRELIEQLRNKPSDLGTKLQDPRIMTTLSVLLGVDLGSMDEEEEIATPPPPPPPKKETKPEPMEEDLPENKKQALKEKELGNDAYKKKDFDTALKHYDKAKELDPTNMTYITNQAAVYFEKGDYNKCRELCEKAIEVGRENREDYRQIAKAYARIGNSYFKEEKYKDAIHFYNKSLAEHRTPDVLKKCQQAEKILKEQERLAYINPDLALEEKNKGNECFQKGDYPQAMKHYTEAIKRNPKDAKLYSNRAACYTKLLEFQLALKDCEECIQLEPTFIKGYTRKAAALEAMKDYTKAMDVYQKALDLDSSCKEAADGYQRCMMAQYNRHDSPEDVKRRAMADPEVQQIMSDPAMRLILEQMQKDPQALSEHLKNPVIAQKIQKLMDVGLIAIRSTIP1 peptide from cancer cell line SEQ ID NO: 4 DPQALSEHLKSTIP1 peptide from cancer cell line SEQ ID NO: 5 AMADPEVQQIMSDPAMRSTIP1 peptide from cancer cell line SEQ ID NO: 6 AALEFLNRSTIP1 peptide from cancer cell line SEQ ID NO: 7 TYEEGLKHEANNPQLKSTIP1 peptide from cancer cell line SEQ ID NO: 8 LILEQMQKSTIP1 peptide from cancer cell line SEQ ID NO: 9 LDPHNHVLYSNRSTIP1 peptide from cancer cell line SEQ ID NO: 10 LAYINPDLALEEKSTIP1 peptide from cancer cell line SEQ ID NO: 11 LMDVGLIAIRSTIP1 peptide from cancer cell line SEQ ID NO: 12 NPVIAQKIQKLMDVGLIAIRSTIP1 peptide from cancer cell line SEQ ID NO: 13 EGLQNMEARSTIP1 peptide from cancer cell line SEQ ID NO: 14 DCEECIQLEPTFIKSTIP1 peptide from cancer cell line SEQ ID NO: 15 LLEFQLALKSTIP1 peptide from cancer cell line SEQ ID NO: 16 KAAALEFLNRSTIP1 peptide from cancer cell line SEQ ID NO: 17 ALDLDSSCKSTIP1 peptide from cancer cell line SEQ ID NO: 18 FMNPFNMPNLYQKSTIP1 peptide from cancer cell line SEQ ID NO: 19 ALSVGNIDDALQCYSEAIKSTIP1 peptide from cancer cell line SEQ ID NO: 20 HYTEAIKSTIP1 peptide from cancer cell line SEQ ID NO: 21 NPVIAQKSTIP1 peptide from cancer cell line SEQ ID NO: 22 TLLSDPTYRSTIP1 peptide from cancer cell line SEQ ID NO: 23 HDSPEDVKRSTIP1 peptide from cancer cell line SEQ ID NO: 24 DAIHFYNKSTIP1 peptide from cancer cell line SEQ ID NO: 25 KDFDTALKSTIP1 peptide 445 (amino acid position 445-469 of full-length STIP1)SEQ ID NO: 26 TKAMDVYQKALDLDSSCKEAADGYQSTIP1 peptide 458 (amino acid position 458-482 of full-length STIP1)SEQ ID NO: 27 DSSCKEAADGYQRCMMAQYNRHDSPSTIP1 peptide 470 (amino acid position 470-494 of full-length STIP1)SEQ ID NO: 28 RCMMAQYNRHDSPEDVKRRAMADPESTIP1 peptide 495 (amino acid position 495-519 of full-length STIP1)SEQ ID NO: 29 VQQIMSDPAMRLILEQMQKDPQALSSTIP1 peptide 507 (amino acid position 507-531 of full-length STIP1)SEQ ID NO: 30 ILEQMQKDPQALSEHLKNPVIAQKI

What is claimed is:
 1. A method for inhibiting cancer cell growth,comprising the step of administering an effective amount of isolatedpolypeptide comprising the amino acid sequence SEQ ID NO: 1 to a subjectin need thereof, wherein the cancer cell expresses STIP1.
 2. The methodof claim 1 wherein the cancer is selected from the group consisting ofpancreatic cancer, endometrial cancer, lung cancer, nasopharyngealcarcinoma, breast cancer and colon cancer.
 3. The method of claim 1further comprising the step of administering an antibody against STIP1.4. A method for inhibiting cancer cell growth in a subject, the methodcomprising the step of administering an effective amount of an antibody,or an antigen-binding portion thereof, binding to the peptide having theamino acid sequence of SEQ ID NO: 1, wherein the cancer cell expressesSTIP1.
 5. The method of claim 4 wherein the cancer is selected from thegroup consisting of pancreatic cancer, endometrial cancer, lung cancer,nasopharyngeal carcinoma, breast cancer and colon cancer.
 6. The methodof claim 4 further comprising administering an isolated polypeptidecomprising an amino acid sequence of SEQ ID NO: 1.